The invention relates to an insulation system for internal thermal insulation of a pressure chamber which can be pressurized or subjected to pressure by a gas flow, the system being constructed for arrangement at an inner surface of an outer jacket of the pressure chamber and comprising at least one layer of insulating material.
It further relates to a method of internal thermal insulation of a pressure chamber which can be pressurized or subjected to pressure by a gas flow, comprising an insulation system constructed for arrangement at an inner surface of an outer jacket of the pressure chamber and comprising one or more layers of insulating material.
Insulation systems and methods of this type are used particularly for thermal insulation of pressurized volumetric solar radiation receivers, in which a gas absorbs heat from concentrated solar radiation in an absorber and the heated gas is drawn off. As the insulation systems used are not generally of gas-tight construction pressure equalization or balancing takes place during operation, i.e. pores of the insulating material are filled with the gaseous medium of the gas flow applied to the material until the pressure in the insulation system is equal to that of the surrounding gaseous medium. Since the inoperative state of such a receiver is usually a depressurized state, pressure equalization takes place particularly when an installation including the receiver is started or shut down. When the installation is shut down the pressure in the insulating material drops and a gas flow passes out of the insulation system, whereby particles may be entrained from the material. A quartz window through which solar radiation passes into the receiver may in particular be fouled in the process. The window is consequently exposed to excessive absorption, which may cause degradation of the window material. This leads to a great deal of cleaning and maintenance work on the receiver.